The present invention relates to an ignition control process in a cylinder of an internal-combustion engine, having an ignition coil whose primary winding is switched and a secondary winding thereof being connected with a spark plug, as well as an ignition control unit which, by way of a line, controls a switching logic switching the primary winding.
A process for the ignition control of the above mentioned type is known from German Patent document DE 101 38 976 A. As a rule, this process is used in the case of an internal-combustion engine having a single-coil ignition system, in which a correspondingly switched ignition coil, and a spark plug connected therewith, are assigned to each cylinder. Several of these single-coil ignition systems are switched by an ignition control unit. As a rule, the switching logic assigned to each single-coil ignition system is also arranged in the single-coil ignition system. Its switching action, for example, for the start and the termination of the charging of the primary winding, is determined by the ignition control unit.
The ignition control unit itself is arranged at a spatial distance from the cylinders and is connected with the switching logics by way of individual electric lines. These lines are problematic with respect to electromagnetic compatibility because electric irradiation and, thereby, interferences with the signal transmission may occur which are caused by the high electrical fields.
It is an object of the present invention to provide an ignition control process of the above-mentioned type by which the signal transmission between the ignition control unit and the switching logics is implemented largely free of interferences.
This object is achieved by a process for the ignition control in a cylinder of an internal-combustion engine, having an ignition coil whose primary winding is switched and a secondary winding thereof being connected with a spark plug, as well as an ignition control unit which, by way of a line, controls a switching circuit logic switching the primary winding. At the start of a power cycle, a switching signal is transferred from the ignition control unit to the switching logic, which switching signal marks the start of the power cycle, and whose length of time is used as the reference length (idle time) for additional digital control information transferred from the ignition control unit to the switching circuit logic.
According to the invention, a further development is provided for the signal transmission between the ignition control unit and the switching logics, which switching signal marks the start of the power cycle, and whose length of time is used as the reference length (idle time) for additional digital control information transferred from the ignition control unit to the switching logic. As a result, fusing the length of time of this switching signal as the reference length, high-expenditure time bases in the switching logics can be eliminated. Synchronization measures required in the case of several time bases also become superfluous for these time bases. A process is therefore obtained which is largely protected from interfering influences and is connected with low expenditures.
Advantageous further developments of the invention are described and claimed herein.
Other objects, advantages and novel features of the present invention will become apparent from the following detailed description of the invention when considered in conjunction with the accompanying drawings.